Day16 - IOCTL Control Plane

Objective

Implement and test ioctl interface for mygpio driver.

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IOCTL Commands

1. Set Debounce

#define MYGPIO_IOC_SET_DEBOUNCE \
    _IOW(MYGPIO_IOC_MAGIC, 1, struct mygpio_ioc_debounce)

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2. Get Status

#define MYGPIO_IOC_GET_STATUS \
    _IOR(MYGPIO_IOC_MAGIC, 2, struct mygpio_ioc_status)

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3. Clear Events

#define MYGPIO_IOC_CLR_EVENTS \
    _IO(MYGPIO_IOC_MAGIC, 3)

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Driver Implementation (Key Part)

static long mygpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    ...
}

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Build

make
sudo insmod mygpio.ko

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Test Programs

1. SET_DEBOUNCE

./test_ioctl_set_debounce 100

Expected:

• dmesg shows debounce updated

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2. GET_STATUS

./test_ioctl_get_status

Expected output:

version        : 1
led1           : 0
led2           : 0
button         : 0
pending_events : 0
debounce_ms    : 20

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3. CLR_EVENTS

./test_ioctl_clear

Expected:

• event queue cleared

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Functional Tests

Test A: LED Control

echo led1=1 > /dev/mygpio
./test_ioctl_get_status

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Test B: Debounce Update

./test_ioctl_set_debounce 80
./test_ioctl_get_status

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Test C: Button Events

1. Press button multiple times
2. Check:

./test_ioctl_get_status

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Test D: Clear Events

./test_ioctl_clear
./test_ioctl_get_status

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Result

All ioctl commands:

• work correctly
• update driver state as expected
• integrate with event system

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Conclusion

Control plane successfully implemented using ioctl.